The present invention relates to surfactant mixtures used as wetting agents and/or as emulsifiers in agrochemical preparations, particularly in pesticide compositions.
The pesticide active ingredientsxe2x80x94according to the characteristics of the actives and of their intended applicationsxe2x80x94can be formulated as dusts, wettable powders, dispersible granules, suspension concentrates, emulsifiable concentrates, emulsions and concentrated solutions, and their application as formulated products on soil, seeds or plant foliage is generally carried out with aqueous spray in form of solution, suspension or emulsion.
Surfactants are commonly used in order to disperse and suspend the solid substances, or to emulsify the oily liquids in water, forming suspensions or stable emulsions. The surfactants help the formation of aqueous dispersions of compounds insoluble in water. Moreover the surfactants reduce the surface tension between aqueous spray and the material (soil, seeds, foliage) to be treated, thus favouring the spreading of droplets on the treated surface and the penetration of the active ingredient into the materials.
Among surfactants, which can be used for the aforementioned purposes, the aliphatic polyglucosides have been known for a long time. These materials offer several advantages due to their low toxicity and good biodegradability, and even have certain fungicide, insecticide, and acaricide activities. Due to these features, the organic polyglucosides provide, in agrochemical formulations and applications, a wider spectrum of functions, since other equivalent traditional surfactants are normally used only as wetting agents and/or emulsifiers.
For instance, U.S. Pat. No. 4,888,325 describes pesticide compositions that contain alkylglucosides, alone or in combination with other surfactants. However, such compositions show weak wetting performance and cannot sufficiently reduce the interfacial tension between the aqueous spray and the material on which said spray is applied.
U.S. Pat. No. 5,385,750 describes the use of aliphatic polyglucosides as co-adjuvant in pesticide formulations in combination with fatty alcohol. According to U.S. Pat. No. 5,385,750 the addition of fatty alcohol to the alkylpolyglucosides increases its wetting performance, favouring the penetration of the pesticide active ingredient into biological materials, even when the treated surface layers are waxy or oily as in the case of foliage.
On the other hand, the presence of a fatty alcohol creates considerable drawbacks: it gives bad odours and causes a noticeable lowering of the emulsifying ability of the alkylpolyglucosides.
Therefore, it is still an unresolved problem to obtain compositions based on aliphatic polyglucosides having better wetting properties, maintaining good emulsifying characteristics, without the drawbacks experienced with the known products as described above.
Now the Applicant has found that the use, as wetting agent and/or emulsifier, of a mixture comprising at least an alkylpolyglucoside, at least an anionic derivative of an alkylpolyglucoside and at least an anionic derivative of a fatty alcohol, in suitable weight ratio, has unexpected advantages in the application of agrochemical preparations on soil, seeds and plants, particularly when aqueous sprays of pesticide formulations are used.
These surfactant mixtures show the required efficacy in the formation of stable systems with water and organic substances and, moreover, they increase the penetration of the pesticide active ingredient into biological materials, due to a superior wetting power as compared to that of aliphatic polyglucosides used alone.
Additionally, the substances contained in the present mixtures are quickly biodegradable and satisfy the request of low toxicity for the mammals and low irritating effect in contact with the epidermis, thus being suitable for the use in pesticide preparations to be applied on edible plants; the mixtures of the present invention are indeed free of harmful or toxic by-products, like amines, ethylene oxide, 1,4-dioxane, alkyl phenols, etc.
Therefore the subject of the present invention is a surfactant mixture suitable for the use as wetting agent and/or emulsifier in pesticide agrochemical compositions, characterised by comprising:
A) at least an alkylpolyglucoside,
B) at least an anionic derivative of an alkylpolyglucoside, and
C) at least an anionic derivative of a fatty alcohol.
Further subjects of the present invention are the aqueous compositions of pesticides comprising such surfactant mixture, and their use in agriculture for the treatment of seeds, plants and soil.
The characteristics and the advantages of the surfactant mixtures according to the present invention will be illustrated in detail in the following description.
The present surfactant mixture comprises at least an alkylpolyglucoside, at least an anionic derivative of an alkylpolyglucoside and at least an anionic derivative of a fatty alcohol.
Examples of alkylpolyglucosides, according to the aim of the present invention are the aliphatic alkylpolyglucosides represented by the following formula (I)
Rxe2x80x94Oxe2x80x94(G)xxe2x80x83xe2x80x83(I)
where:
R is a saturated or unsaturated aliphatic group having from 6 to 20 carbon atoms, linear or branched;
O is an oxygen atom;
G is a residue of a reducing saccharide connected to Rxe2x80x94O by means of an ethereal O-glycosidical bond;
x is a number from 1 to 10, representing the average degree of oligomerization of G.
Preferably R is an alkyl group having from 8 to 16 atoms of carbon, G is a residue of a reducing saccharide and x is a number between 1 and 2.
The preferred alkylpolyglucosides, according to the invention, are compounds of formula (I) in which G is a residue of glucose.
The compounds of formula (I) are known, as well as their methods of preparation, and are for instance described in U.S. Pat. Nos. 3,219,656, 3,547,828 and 3,839,318.
Preferred compounds of formula (I) reported above are commercially available products and are endowed with an high biodegradability.
Examples of anionic derivatives of alkylpolyglucosides according to the aim of the present invention are compounds represented by the following formula (II)
[Rxe2x80x2xe2x80x94Oxe2x80x94(G)x]nxe2x80x94(D)yxe2x80x83xe2x80x83(II)
where:
Rxe2x80x2 is a aliphatic group, saturated or unsaturated, linear or branched, having from 6 to 20 atoms of carbon, preferably from 8 to 16 atoms of carbon;
G is a residue of a reducing saccharide, preferably of glucose, connected to Rxe2x80x2xe2x80x94O by means of an ethereal O-glycosidical bond;
O is an oxygen atom;
D is an acyl residue connected to an oxygen atom of the residue G, and derived from a bicarboxylic acid or a polycarboxylic acid having an aliphatic chain from 2 to 8 carbon atoms, linear or branched, saturated or unsaturated, not substituted or substituted with one or more hydroxyl groups, and in which at least one carboxylic group is salified or in acid form;
n is a number between 1 and mxe2x88x921, where m is the number of carboxylic groups in the acid that originates D;
x has the same meaning as described above for the compounds of formula (I);
y is a number from 1 to 10 representing the degree of average esterification of (G)x.
Preferred anionic derivatives of alkylpolyglucosides according to the present invention, are compounds of formula (II), in which Rxe2x80x2 is an alkyl group having from 8 to 16 atoms of carbon and D is the acyl residue of a carboxylic acid selected from the group consisting of citric acid, tartaric acid, maleic acid and malic acid.
The above mentioned anionic derivatives of alkylpolyglucosides of formula (II) are known and they can be prepared as described, for example, in EP 258 814, or in EP 510 564.
Examples of anionic derivatives of fatty alcohols according to the present invention are represented by the following formula (III)
Rxe2x80x3xe2x80x94Oxe2x80x94Dxe2x80x2xe2x80x83xe2x80x83(III)
and they can be prepared by esterification of a carboxylic acid with a fatty alcohol of formula Rxe2x80x3xe2x80x94OH, where:
Rxe2x80x3 is an aliphatic group, saturated or unsaturated, linear or branched, having from 6 to 20 atoms of carbon, preferably from 8 to 16 atoms of carbon;
O is an oxygen atom;
Dxe2x80x2 is an acyl residue of a bicarboxylic acid or of a polycarboxylic acid having an aliphatic chain with from 2 to 8 atoms of carbon, saturated or unsaturated, linear or branched, not substituted or substituted with one or more hydroxyl groups, and in which at least one carboxyl group is salified or in its acid form.
Preferred anionic derivatives of fatty alcohols according to the present invention are compounds of formula (III) in which Dxe2x80x2 is an acyl residue of a carboxylic acid selected from the group consisting of citric acid, tartaric acid, malic acid and maleic acid.
An example of preparation of the anionic derivatives of fatty alcohols of formula (III) has been reported in the article xe2x80x9cCitric Ester Surfactantsxe2x80x9dxe2x80x94P. J. Borchert et al.xe2x80x94Proceeding of the World Surfactants Congressxe2x80x94Munich 1984, vol. 2, pag. 147. Particularly relevant for the realisation of the present invention are the anionic derivatives of alkylpolyglucosides (II) and the anionic derivatives of fatty alcohol (III) in which D and Dxe2x80x2 are acyl residues of citric acid with at least one carboxylic group salified, preferably in the form of sodium salt.
In the surfactant mixture according to the present invention, the R group in the compound of formula (I), the Rxe2x80x2 group in the compound of formula (II) and the Rxe2x80x3 group of the fatty alcohol of formula (III) can be equal or different from one another; surfactant mixtures in which R=Rxe2x80x2=Rxe2x80x3 have wetting and emulsifying power particularly high.
Similarly, in the surfactant mixture according to the present invention, the D group in the compound of formula (II) and the Dxe2x80x2 group in the compound of formula (III) can be equal or different from one another; the surfactant mixtures in which D=Dxe2x80x2 have wetting and emulsifying power particularly high.
According to the present invention, particularly preferred are surfactant mixtures in which R=Rxe2x80x2=Rxe2x80x3 and simultaneously D=Dxe2x80x2.
In the present surfactant mixture composition the quantity of each component ranges between 1 and 98% by weight with respect to the total weight of the mixture.
According to a preferred embodiment of the present invention, the surfactant mixture composition, expressed as percentage by weight of each component with respect to the total weight of the mixture, is the following:
The present surfactant mixture may comprise from 0 to 97% by weight of water with respect to the total weight of the mixture.
The surfactant mixture of the present invention can be used to formulate active ingredients in form of wettable powders, dispersible granules, concentrated suspensions, concentrated emulsions, microemulsions, macroemulsions, microencapsulated products, solutions, etc., thus obtaining a composition to be applied as such, or in a diluted form with water or with other appropriate solvent at the required dilution ratio; said composition can be prepared at the required dilution right before use too.
In a particular embodiment of the invention, it is generally preferred to add the present surfactant mixture to the formulated pesticide, and then to dilute with water to the desired concentration in order to obtain an aqueous sprayable composition of the formulated pesticide.
According to a particular embodiment of the present invention, the agrochemical compositions comprising the surfactant mixture, comprise at least an active ingredient, for example with pesticide action, and a carrier, for instance water; preferably, in such compositions the quantity of surfactant mixture is from 1 to 90% in weight, with respect to the total weight of the composition, the quantity of the active ingredient is from 1 and 90% by weight, while the quantity of carrier makes up the balance of the composition.
Said agrochemical compositions can further comprise:
one or more active ingredients with various functions, for instance insecticide, acaricide, fungicide, nematocide, disinfectant, herbicide, fertilizer or micronutrient;
other surfactants, besides those of the surfactant mixture subject of the invention;
other products, such as antifoam agents, antifreeze agents, dyes, stabilisers and buffers;
usual additives of agrochemical compositions.
Preferably, the present surfactant mixture is used in aqueous spray formulations of pesticides, comprising for example:
said surfactant mixture in an amount from 0.1 to 20% by weight with respect to the total weight of the composition, preferably from 1 to 10% by weight;
the concentrated formulation of the pesticide active ingredient, in quantity between 0.1 and 20% by weight;
water,
and, optionally, other concentrated formulations of active ingredients, micronutrients, other surfactants and/or other additives commonly used in the agrochemical compositions, in such an amount which makes up the balance of the composition.
Said agrochemical compositions can comprise pesticide active compounds, such as Acephate, Acetochlor, Alachlor, Alphacypermethrin, Amitraz, Atrazine, Benomyl, Bentazon, Bromacil, Captan, Carbaryl, Carbendazim, Carbofuran, Carboxin, Chloridazon, Chlorpyriphos, Chlorthalonil, Chlortoluron, Copper oxychloride, Copper oxyquinolate, Cypermethrin, Cyromazine, Dalapon, Deltamethrin, Diazinone, Dicamba, Dichlorprop, Dicofol, Dimethoate, Dinocap, Diuron, Dodine, Endosulfan, Ethofumesate, Ethylparathion, Fenitrothion, Fenthion, Fentin Hydroxide, Fluometuron, Folpet, Fosetyl-AI, Glufosinate, Glyphosate, Lindane, Linuron, Malathion, Mancozeb, MCPA, MCPB, Metalaxyl, Methamidophos, Methomyl, Methylparathion, Metobromuron, Metolachlor, Naled, Oxadiazon, Paraquat, Pendimethalin, Permethrin, Phenmedipham, Pyperonilbutoxide, Pirethrum, Propachlor, Propanil, Propiconazol, Propisochlor, Propoxur, Quizalofop-P-tefuryl, Sethoxydim, Simazine, Sulphur, Temephos, Tetraconazol, Tetramethrin, Thiophanate methyl, Thiram, Triadimefon, Triadimenol, Trifluralin, Vinclozolin, Zineb, Ziram, and their mixtures.
The surfactant mixture of the present invention is particularly suited for agrochemical formulations comprising N-(phosphonomethyl)glycine (Glyphosate) or its salts, preferably the isopropylammonium salt of N-(phosphonomethyl)glycine (Glyphosate isopropylammonium), which is from here on referred to as Glyphosate IPA.
The Applicant has found that the use of said surfactant mixture in dilutable with water or aqueous compositions of pesticides has an emulsifying effect and wetting performance, which can help the formation of an homogeneous dispersion of the pesticide in water, thus accelerating its penetration in the treated biological materials (soil, seeds or plant foliage), in an unexpectedly higher degree as compared to the known prior art where only alkylpolyglucosides are used.
The aforementioned characteristics of said surfactant mixtures are determined by measurement of the superficial tension and determinations of the wetting power, as illustrated in the following Examples.